60 CLINICAL BACTERIOLOGY AND H^MATOLOGY 



from the sputum. The mucus may be collected on a diphtheria 

 swab or on a platinum lo'op, or by means of one of the angled 

 pipettes described on p. 157, though it is often too thick to be 

 sucked up into such a narrow tube. 



Films are prepared from the sputum by squeezing a small 

 mass between two slides and sliding them apart. Dry and fix 

 by heat. Two should be prepared. The first should be 

 stained by Gram's method, and counterstained by neutral red 

 or dilute carbol fuchsin for a quarter of a minute, then washed, 

 dried, and mounted. The other is to be stained more deeply 

 with carbol fuchsin or LofHer's blue about five minutes with 

 gentle heat in either case. The influenza bacillus stains with 

 difficulty, and may not be seen in the Gram's specimen which 

 is lightly counterstained. And there is a good reason for not 

 carrying the counterstaining too far in the former case, since 

 if the carbol fuchsin is used for too long a time it may dis- 

 place the violet stain of an organism which retains Gram. 



The influenza bacillus is an extremely minute organism, 

 and one which requires the highest powers of the microscope 

 for its study. It is an extremely minute rod, so small that it 

 would take from eig'ht to sixteen of these rods to make up 

 the diameter of a red blood-corpuscle. It occurs in vast 

 numbers in the sputum or nasal mucus, and are frequently 

 found within the leucocytes, and when in this situation may 

 appear to have a capsule, being contained in vacuoles in the 

 protoplasm (Plate II., Fig. 3). They are often arranged in 

 pairs, in which case they might be mistaken for 'small but 

 unusually elongated pneumococci, but for the fact that they 

 do not stain by Gram's method. 



These features are sufficient to identify them for clinical 

 purposes. Cultures are difficult to obtain, since the organism 

 only grows in presence of haemoglobin e.g., on agar tubes 

 streaked with sterile blood (see p. 103).* Under these circum- 

 stances they form very minute translucent colonies, much like 

 those of the pneumococci, and cultures have a great tendency 

 to die out. 



The vaccine treatment of influenza or nasal catarrh due to 

 this organism is not very satisfactory. The usual com- 



* Pfeiffer's bacillus grows readily on a medium prepared by adding to a 

 tube of melted agar about one-tenth of its volume of whole or defibrinated 

 blood, boiling for two minutes and allowing it to cool without filtration. The 

 blood may conveniently be squeezed from the finger, as described on p. 35. 



